A presidential commission yesterday recommended that the government pay each of the American hostages held in Iran $12.50 tax-free for each day of captivity.

If the plan is approved by President Reagan and Congress, each of 51 former hostages held for 444 days would receive $5,550, in addition to salaries and other benefits already authorized. The new payment would cost the treasury about $290,000 for all the hostages, including several released after shorter periods of confinement.

Reactions from the hostages and their lawyers ranged from restrained to indignant. "That $12.50 is a little under 1/15th of what the commission members received each day for serving on the commission," sniped hostage attorney John Coale, who represents 13 blacks, women and others who were freed or escaped after a few weeks.

The commission held that the rate, adjusted for inflation, was similar to benefits paid prisoners of war and civilians captured during the Korean and Vietnamese wars and in the 11-month Pueblo spy ship capture by North Korea in 1968.

The commission decided against extending the benefits to Jerry Plotkin, a civilian businessman among the 52 hostages released in January. The government has "no legal or moral responsibility" to provide such compensation to private citizens traveling abroad, the 132-page report said, particularly since warnings against travel in the area had been issued.

The $12.50 would be in addition to salaries and a range of medical and other benefits provided the hostages and their families under the recently enacted Hostage Relief Act, which the commission said has dealt effectively with the worst problems by "alleviating economic hardships," restoring property losses and providing payment of medical bills.

In addition to the $12.50 payment, the nine-member commission made seven other proposals, including:

The time limit on reimbursement for medical costs resulting from captivity be removed.

The maximum payment allowable on claims for damage or loss of personal property by raised from $40,000 to $50,000.

Hostages be protected from disclosing to employers psychiatric or psychological treatment which might be damaging to their careers by arranging for outside intermediaries to receive and authorize payments.

Louisa Kennedy, wife of former hostage Morehead Kennedy, told reporters that the commission was "dealing in symbolism" and that $12.50 was a "good symbolic figure."

Although she said there is "no way the hostages and their families can be compensated for the 14 months of hell they went through," she said the American people had provided a kind of compensation by welcoming the hostages home with such warmth.

Joseph Subic, the only ex-hostage to be denied a medal by the Army for statements he made during captivity, called the recommendation a "bloody insult." Now a student at George Washington University, he said the controversy surrounding him since his return has made him "persona non grata" to many potential employers.

Dorothea Morefield, wife of ex-hostage Richard Morefield, said the amount was "acceptable" as a token but added that she would rather have collected it from Iran than from the American taxpayer.

Lawyers had argued that the hostages were entitled to "compensatory damages" from the United States because, under the agreement to secure the hostages' freedom, the Carter administration signed away their rights to sue the Iranian government for damages. The Supreme Court upheld the government's authority to do so.

The commission yesterday specifically recommended against any U.S. payment which might be construed as compensatory damages.

Many Vietnam veterans resented an earlier suggestion by a hostage attorney that compensation totaling $23 million would be fair. As one testified to the commission, any compensation would be a "deliberate slap in the face" to the Americans who fought in that war "only to be scorned by their government and countrymen."

The commission, which had studied the compensation question nearly three months, was chaired by James S. Dwight, partner in an international accounting firm, and included former secretary of state Cyrus R. Vance and former Health and Human Services secretary Patricia Roberts Harris.